The present invention relates to a tool for crimping contact elements on electrical conductors, in particular a crimping tool with pressing or mouth jaws.
Pressing tools for crimping of contact elements, such as contact bushes, cables shoes and sleeve connectors are known in different embodiments and have been used for many years. They have pressing or mouth jaws which are beak-shaped or are closed parallel and carry a pressing profile. They are brought to closing and pressing position by means of their handles.
In view of the fact that with the beak-shaped closing pressing and mouth jaws there are disadvantages of partially incomplete or non uniform crimping of both contact parts and in view of the increasing demands in the consumer industry for the quality of the pressing connections produced with such tools, there is lately a tendency to improvement of the pressing technique. As a result, tools are utilized which have pressing or mouth jaws movable parallel to one another. When the tools of this type are utilized, an efficient crimping can be provided with an optimal efficient flat contact between both parts to be joined. The pressing tools of this type has however the disadvantage with regard to the pressing or mouth jaws closeable in a beak-like manner, in that the design of their active tool elements, the pressing jaw arrangement and their guidance involve high structural expenses to convert the pliers-like working movement of the handle pair over the lever pivot point into a parallel closing movement of the pressing jaws.
For example, there is a known pliers design of this type, which includes the mouth jaws operating as a pressing plunger which is directly associated in a specific mouth jaw serving as a pressing die. In otherwords, with the spacially fixedly arranged guide it is slidingly movably received, and its head part is pivotably supported on another tongue lever for transmission of the applied pressing forces. This design is basically acceptable for simple parallel crimping. However, it is usable only conditionally for completely responsive, reliably operating and functionally complete crimping works, since this type of pressing plunger receptacle and the guidance of the same under the action of the pressing forces frequently do not satisfy all requirements.
Another known parallel pressing pliers are designed with a toggle leverdrive because of the availability of relatively high pressing forces. It includes a lever which is directly pivotably connected with a cylindrically guided pressing plunger movable parallel on the pressing die. This solid construction of this type tool leaves plenty to be desired in the functional sense. The tool is relatively heavy because of the required stability and therefore is difficult to handle, which condition can be compensated only partially by simple and fast exchangeable pressing jaws.
Generally speaking it has been found that with both above mentioned tool construction the structural and manufacturing advantageous properties step to certain degree are overshadowed by different disadvantages in functional aspects, and visa versa. While with the beak-shaped closing pressing and mouth jaws the advantage is provided with respect to the applied pressing forces which can be adjusted with simple means to the corresponding required force consumption by arranging the great pressing cross-section directly at the tool hinge and by placing and arranging the smaller pressing cross-sections due to the non equal smaller force consumption after the mouth opening, in the tools with the parallel closing pressing and mouth jaws this is disadvantageous. Therefore such a manipulation of the applied pressing forces is excluded, since the forces applied in the force-transmitting system of this type of tool at each point of the pressing or mouth jaws act with the same magnitude. Moreover, the parallel closing movement realized with this tool type with respect to the design of the uniform pressing in the total shaping region, in particular in the case of 6-edge and roll pressing provides advantageous results, since here differently dimensioned working or pressing strokes can not occur in the region of the individual pressing forms and thereby the form non-uniformities are reliably prevented.
In practice, there is however no tool which can combine the advantages of both types of tools, and at the same time can be produced in a simple and cost-favorable manner and also provide identically great pressing forces.